1. Field of the Invention
The invention relates to the detection of a biological entity in a sample. More particularly, the invention relates to detection of specific pathogens from a possible presence of one to hundreds to thousands of pathogens.
2. Summary of the Related Art
Crowding and unrest in the modern world has created the potential for rapid spread of disease, either through terrorism in the form of germ warfare, or simply through disease transmission among densely packed hosts in urban environments. Wade, New York Times, Nov. 21, 1997, discloses that one gram of anthrax, about the weight of two paper clips, contains enough doses to kill ten million people. Many other pathogenic organisms could similarly be used by terrorists, and it would be difficult to know which pathogens were being used before it was too late to avoid illness and death. In addition, in urban environments widespread epidemics may be more likely to happen, due to the close proximity of diseased and healthy people. In such instances, it could be critical to determine at an early stage what pathogen is involved to provide effective treatment and/or prophylaxis. Moreover, when natural disasters, such as flooding or earthquakes occur, frequently widespread disease follows in the aftermath. Effective relief requires the ability to rapidly identify any pathogen causing such an outbreak.
Unfortunately, current methodologies do not allow simultaneous screening for specific pathogens among a possible hundreds to thousands of pathogens. Current methodologies include antibody-based assays, DNA chip assays and assays based on polymerase chain reaction. Chee et al., U.S. Pat. No. 5,861,242 (1999) discloses an array of nucleic acid probes on biological chips for diagnosis of HIV. Crowl et. al., U.S. Pat. No. 5,773,210 (1998) discloses an assay for HIV utilizing an envelope protein from the virus to detect antibodies to the virus in patient's serum. Grattard et al., J. Clin. Microbiol. 32: 596–602 (1994) discloses the use of PCR to detect Enterobacter cloacae in a nosocomial outbreak. Unfortunately, all of these methodologies are limited to the detection of a single species of pathogen. There is, therefore, a need for new assays that can detect the presence of one or more biological entity in a sample out of a possible number of hundreds to thousands of distinct biological species.